Hormones and body defenses

Hormones increase blood flow through the brain and nervous system, consequently allowing more viruses to reach these areas. The levels of both hormones are known to increase somewhat under stressful conditions. Thus, unusual stress at a time when viruses are in the blood may increase the hormone levels and their effects on blood flow enough to facilitate viral invasion of the nervous system. It is best to stay in bed until fever is gone. 

Too many people with contagious diseases get out of bed too soon, risking complications for themselves and increasing the likelihood of infecting others. Nursing mothers with colds should ask their doctor about wearing a nose-and-mouth mask when handling their baby. Infection from Food and Water Typhoid, amoebic dysentery, and bacterial dysentery are among dis- eases that gain footholds through the mouth. Typhoid germs appear in food, milk, and water that have been contaminated by fecal matter.

Flies that have fed on such matter may carry the germs to food and drink. Every precaution should be taken to keep food from being exposed to flies, especially warm food. Plastic dish covers are practical. Habits of cleanliness should be encouraged for all family members. 302 / Preventive Body Care Washing hands after use of the toilet and before preparing and eating food should be automatic. This is important because contamination can be spread by a person not himself ill, as in the case of a typhoid carrier. Exemplifying this is the classic story of Typhoid Mary, an otherwise healthy carrier who, as a cook, went from job to job and spread typhoid to more than 100 victims. All the milk you use should be pasteurized, not just certified.

 Certified milk may not be safe, because certification of the health of cattle is not foolproof; also certified milk is handled before it is bottled.

Pasteurization heats milk for 30 minutes at 142°F or for one minute at 160°F, After the heat process, the pasteurized milk goes directly into sterilized bottles without being touched by human hands. Unpasteurized milk may carry the agents not only of typhoid but also of tuberculosis, brucellosis, and other diseases. If at any time you are in doubt about milk, you can do your own home pasteurization by boiling for 3 minutes or scalding the milk for 30 minutes in a double boiler. In cities, water supply is usually safe. 

In the country, be cautious. No matter how clear water may look, it may come from wells or lakes, ponds or rivers containing many disease organisms. Unless you are certain of purity, boil for 10 minutes before drinking. 

Body defenses and Immunity against Bacteria and viruses and worms

BODY DEFENSES

 In the past, infectious diseases took a huge toll. Less than a century ago, every fifth child died before reaching his first birthday, and almost as many more died before reaching the age of two, most of them from dysentery and various childhood infectious diseases. Epidemics of diphtheria have been known to kill every child under 12 in an entire com- munity.

Plagues of smallpox, yellow fever, and other diseases are decimated populations. Until medicine learned about microorganisms, there was little that could be done to prevent disease-other than what the body itself could do. And, fortunately, the body is not helpless against germs; else man would have ceased to exist at all long ago. Against an overwhelming influx, body defenses, as already noted, may not suffice. But those defenses, day in and day out, serve to prevent many instances of what otherwise could be serious disease. There are actually several lines of defense, and it is important to under- stand all of them. The first line prevents organisms from gaining entrance. The skin itself is part of this vital defense.

Unless broken by a wound, it is practically microbe-proof. Organisms lie harmlessly on it. Body openings also are defended. Mucous membranes form a protective lining. In the respiratory passages, the membranes' secretions of mucus form a sticky coating that catches many organisms before they can penetrate farther. Tiny filters, such as the hair in the nose, help keep out germs. Irritation of the mucous membranes leads to coughing and sneezing, which force out germs and irritating substances. Body fluids have defense functions.

Tears wash organisms out of the eyes and, being slightly antiseptic, discourage organism growth. Stomach acid kills many organisms entering with food. Vomiting and diarrhea are part of the defense mechanism, helping to get rid of invading organisms. A second line of defense goes into action when organisms get by the first line. It consists of leukocytes (white blood cells) and tissue cells. As organisms and their poisonous products begin to damage tissue cells, the body increases the blood supply to the infected area, producing an inflammatory reaction. And as cells are destroyed, others form a wall around the invading organisms, aimed at confining them and protecting other body areas. It is this wall that surrounds a boil, infected cut, even a pimple.

Fever, too, develops in many infections and sometimes helps in the destruction of some germs that are unable to thrive at a temperature much above normal body temperature. Meanwhile, the white blood cells are at work. The number in the blood increases rapidly when they are needed to fight infections. Moving into an infected area, the white cells attack and devour the organisms. The infected area becomes a mass of living and dead organisms and white cells, forming the pus that develops in infected tissue. Lymph helps clear out the debris, moving it to the lymph nodes where it is filtered and gradually destroyed.

This is why swollen lymph nodes are indicators of infection in the body. Thus, often, infection is conquered by second-line defense in the tissues, sparing the body more general combat. But if the infection prevails, other body resources are available. The body produces materials called antibodies, which can counteract germs and render their poisons harmless. There are varioustypes of antibodies. One, antitoxin, is highly specific, acting against only a toxin formed by a particular kind of organism. For example, diphtheria anti- toxin neutralizes diphtheria toxin but not scarlet fever or any other kind. Other antibodies, called agglutinins, make certain types of organisms clump together, turning them into easier targets for white blood cells, which surround and devour them. Still other antibodies, bacteriolysins, make certain types of organisms dissolve in the bloodstream.

After the body has won its battle against some types of disease, anti- bodies remain in the blood and prevent the organisms of those particular diseases from getting footholds again. This is what happens when you have measles, chickenpox, or any of the other diseases that people do not get more than once. In such cases, the body becomes immune to the disease; this is called acquired immunity. Many of us are immune to one or more forms of polio because we have had an attack that was so mild we didn't even know we had it, usually mistaking it for flu. Some types of immunity can be passed from mother to child. People, who are immune to a disease withoutever having had are said to have natural immunity.

Some immunityis partial or temporary-that is, they do not completely protect an individual an entire lifetime (a notable example is the common cold).